Abstract:

Histological and Immunohistochemical techniques were used to observe the distribution and quantity of immunocytes，T lymphocytes and its subpopulation，B lymphocytes，Mononuclear/macrophage cells and APCs，then to analyze the immune function and establishment of the crop on histological and cellular level in chicken.The results showed：The lymphoid-tissues are located in the lamina propria at the junction of the crop and the cervical and thoracic parts of the esophagus.A significant count of CD3⁺，CD4⁺，CD8⁺ T lymphocytes are evident in the diffused lymphoid tissues and the interfollicular areas around germinal center where Bu-1b⁺ cells are located in.Parts of CD3⁺，CD8⁺ cells and MHC-Ⅱ⁺ cells are infiltrated to the epitheliums of the mucus and the mucosal glands，which are transformed to the lymphoepithelium；Ma⁺ cells are slightly distributed in the Lamina propria submucosa muscular layer of mucosa and MHC-Ⅱ⁺ emerged in all of the tissues.The results showed that as the first storage place of food in chicken，the crop could be responsible for Moisturizing and softening food through mucus from mucus-producing oesophageal glands in lamina propria；as well as posses histological and cellular capacity of attendant mucosal immunity.The crop is an important part of gut-associated lymphoid tissue (GALT).